In the development of mining machines, particularly for the mining of coal in seams, there have been a number of significant developments which have made the safe and efficient recovery of coal more feasible. For example in U.S. Pat. No. 4,003,602 a mining machine and method were disclosed in which a bore of one size is formed during in cutting using a single barrel cutter, and then by moving rear (wing) cutters outwardly the width of the bore is enlarged during out cutting, utilizing a single auger conveyor to conveyor the cut material. In U.S. Pat. No. 4,889,392 this basic concept was significantly improved upon by utilizing a pair of counter-rotating disc cutters, and re-orienting the rear cutters so that during cutting they initially imparted a forward vector to the cut material during out cutting and then desirably transferred the cut material onto a conveyor which continued movement of the cut material in a forward direction until it was deposited on a main rearwardly moving conveyor. With this system a cob cutter was provided and the bore going in was substantially rectangular. The machine described in the U.S. Pat. No. 4,889,392, particularly when used for high wall mining, allows a substantial force to be applied during advance, and does not cycle as do known commercial mining machines, and therefore is highly advantageous.
While the machine and method disclosed in U.S. Pat. No. 4,889,392 is highly advantageous, it is desirable that the cutting speed thereof be enhanced and that the conveying action thereof be simplified. Therefore according to the present invention a mining machine and method have been developed which achieve these desirable results, enhancing the cutting speed and simplifying the conveying action.
The cutting speed of the mining machine according to the present invention is significantly enhanced (i.e. is between about 75-100% greater) than the cutting speed in the U.S. Pat. No. 4,889,392 primarily by making a few simple changes in the front cutting means. According to the present invention the front cutting means preferably comprise a pair of counter-rotating barrel cutters (such as shown in U.S. Pat. Nos. 2,784,955 and 3,395,941, the disclosures of is which are hereby incorporated by reference herein) in place of the disc cutters, and a cutting chain behind the barrel cutters moving in a plane that is substantially perpendicular to the axes of rotation of the barrel cutters. Such a cutting chain is particularly useful when crawlers are used with the mining machine to advance the mining machine into the tunnel that it forms, and withdraw it from the tunnel. If crawler sections are utilized they are typically placed about every 500 feet along a trailing conveyor. The conveyor trailing the mining machine may be of any suitable conventional type including rubber belt sections, and conveyors such as shown in U.S. Pat. Nos. 5,056,655, 5,087,101, 5,129,502, and/or 5,152,389.
In order to maximize the effectiveness of the conveying action at the mining machine itself, according to the present invention a conveyance surface is provided close to the mine floor. In order to ensure that the cut material (e.g. coal) is properly moved to the conveyance surface rather than pushed under it, the rear (wing) cutters are constructed so that the bottom most portion thereof is approximately at or above the first conveyance surface (e.g. about 2-5 inches off of the mine floor). A reversible motor powers a conventional conveyor chain going over the first conveyance surface to move the cut material rearwardly during out cutting, and that same chain can move over an elevated, second, conveyor surface disposed in operative association with the front cutting means, with a reversible motor moving cut material rearwardly over the second conveyance surface during in cutting. The conveyor construction according to the present invention is thus simplified compared to that in U.S. Pat. No. 4,889,392, and highly advantageous in conveying action compared to that in U.S. Pat. No. 4,003,602.
According to one aspect of the present invention a mining machine for mining an area is provided which comprises the following components: A frame having a front, first and second sides, and a rear. A front cutting means mounted adjacent the front of the frame, and for cutting a volume of material to be mined, and forming a mine floor during cutting. At least two rear cutters located closer to the rear of the frame than is the front cutting means, one rear cutter mounted to each of the frame sides so that it is movable from a first non-cutting position within the volume cut by the front cutting means, to a second, operative, position in which it is outside at least a portion of the volume cut by the front cutting means. A first conveying element mounted by the frame above the mine floor formed by the front cutting means at a position for receipt of material cut by the rear cutters and positioned so that material cut by the rear cutters is moved onto the conveying element for conveyance away from the mined area. And, the rear cutters having bottom-most portions and top portions, and the rear cutters also mounted so that the bottom-most portions thereof are substantially at or above the first conveying element, and above the mine floor.
While the front cutting means may comprise disc cutters or any other type of conventional cutting heads for mining machines, in the preferred embodiment according to the present invention the front cutting means includes a pair of counter-rotating barrel cutters, and preferably also a cutting chain and moving in a plane substantially perpendicular to the axes of rotation of the barrel cutters. Typically first and second barrel cutters and first and second rear cutters are provided, and the first barrel cutter and the first rear cutter are powered by a first explosion proof electric motor while the second barrel cutter and the second rear cutter are powered by a second explosion proof electric motor. A first remote control clutch is provided between the first motor and the first rear cutter and a second remote control clutch between the second motor and the second rear cutter.
The mining machine also preferably further comprises a second conveying element mounted by the frame above the first conveying element and positioned with respect to the front cutting means to convey material cut therefrom away from the mined area. Also crawlers are preferably mounted to the frame for powering the frame into and out of the tunnel formed by the front cutting means and material to be mined. The first and second conveyance elements preferably comprise first and second conveyance surfaces traversed by an endless conveyor chain with connected conveyor flights, the chain powered by a reversible motor. The first and second conveyance surfaces terminate at different levels adjacent the rear of the frame, and the mining machine further comprises conveying means for conveying cut material away from the termination of the first and second conveying surface away from the mined area, such conveying means such as described above with respect to U.S. Pat. Nos. 5,056,655, etc.
The sides of the frame of the mining machine of the invention include elongated openings allowing the passage of material cut by the rear cutters therethrough and onto the first conveying surface. Also the sides of the frame may include forward frame side portions and rear frame side portions, the rear frame side portions pivotally mounted for limited pivotal movement about an axis substantially perpendicular to the frame sides, and the rear frame side portions including the elongated openings therein. Typically a shaft extends between the rear frame side portions and mounts a drive sprocket, and the reversible motor is mounted to one of the rear frame side portions and connected to the shaft mounting the drive sprocket by a telescoping drive. In the preferred embodiment the rear cutter bottom-most portions are about 2-5 inches above the mine floor.
The invention also relates to a method of mining material in an area where no operator will be present. The method comprises the following steps: (a) Cutting into the area to be mined using a mining machine by moving the mining machine in a forward direction, to form a bore having given first dimensions. (b) Removing cut material as the mining machine is moved in the forward direction by moving the material rearwardly out of the area being mined. (c) Terminating forward movement into the area being mined, and then moving the mining machine rearwardly out of the bore while continuing to cut material so as to enlarge the bore from the first dimensions to second dimensions greater than the first dimensions. And, (d) conveying the material cut during rearward movement first in a forward direction, and then ultimately rearwardly so that it moves out of the area being mined in the same manner that the material cut during forward movement is moved out of the area being mined, and wherein step (d) is practiced by cutting the material during rearward movement with cutting chains and drums moving in a direction so as to impart a significant forward force vector to the cut material to push the cut material onto a first rearwardly moving conveyor surface, and moving the cut material on the first conveyor surface rearwardly out of the area being mined.
The method preferably also uses the second conveyor surface vertically above the first conveyor surface, and a common endless chain conveyor moves over the first and second conveyor surfaces powered by a reversible motor. Step (b) is practiced by operating the reversible motor so that the endless chain conveyor moves cut material rearwardly over the second conveyor surface, and step (d) is further practiced by reversing the reversible motor compared to its operation during the practice of step (b), and operating the reversible motor so that the endless chain conveyor moves cut material rearwardly over the first conveyor surface. Step (a) is practiced to form a first mine floor, and step (c) is practiced to cut material with the cutting chain so that a second mine floor, exteriorly of the first mine floor, is formed thereby, the second mine floor being above the first mine floor a sufficient distance so that material cut by the cutting chains will tend to move onto--rather than under--the first conveyor surface.
According to another aspect of the present invention a mining machine for mining in an area is provided comprising the following elements: A frame having a front, first and second sides, and a rear. A front cutting means mounted adjacent the front of the frame, and for cutting a volume of material to be mined, and forming a mine floor during cutting. At least two rear cutters located closer to the rear of the frame than is the front cutting means, one rear cutter mounted to each of the frame sides so that it is movable from a first non-cutting position within the volume cut by the front cutting means, to a second, operative, position in which it is outside at least a portion of the volume cut by the front cutting means. A first conveying element mounted by the frame above the mine floor formed by the front cutting means at a position for receipt of material cut by the rear cutters and positioned so that material cut by the rear cutters is moved onto the conveying element for conveyance away from the mined area. A second conveying element mounted by the frame above the first conveying element, and positioned with respect to the front cutting means to convey material cut therefrom away from the mined area. And, wherein the first and second conveying elements comprise first and second vertically spaced conveyance surfaces traversed by an endless conveyor chain with connected conveyor flights, the chain powered by a reversible motor so that cut material is moved along the first conveyance surface during rearward movement of the frame, and along the second conveyance surface during forward movement of the frame. The details of the conveyance surfaces, and a frame, etc. are preferably as described above.
According to yet another aspect of the present invention a mining machine for mining an area is provided that comprises the following components: A frame having a front, first and second sides, and a rear. A front cutting means including a pair of substantially parallel counter-rotating barrel cutters mounted to the front of the frame and for cutting a volume of material to be mined, and forming a mine floor during cutting. At least two rear cutters located closer to the rear of the frame than is the front cutting means, one rear cutter mounted to each of the frame sides so that it is movable from a first non-cutting position within the volume cut by the front cutting means, to a second, operative, position in which it is outside at least a portion of the volume cut by the front cutting means. And, a non-auger conveyor mounted between the frame sides for conveying material cut by the barrel cutters and the rear cutters away from the barrel cutters. Other components of the front cutting means are preferably as described above, and crawlers are preferably provided.
It is the primary object of the present invention to provide for the efficient and cost-effective removal of mined material from a seam, such as coal, using in cutting and separate out cutting techniques. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.